A wave of explosions targeting Syrian government forces killed dozens of people at a popular Aleppo square Wednesday in an attack for which a Syria-based extremist group has claimed responsibility .

Al-Nusra Front said the strikes were carried out by suicide bombers driving cars packed with explosives , followed by raiders disguised in Syrian military uniforms , according to a statement posted on a website that publishes claims from extreme Islamist groups .

'' The second explosion happened at 8:17 a.m. outside the Governorate Building where a suicide bomber blew up a car bomb loaded with 500 kg of explosive material , '' the Interior Ministry said in a statement .

Two mortar shells also fell near the Municipal Palace , it said .

At least 40 people were killed and about 90 were wounded when three car bombs exploded in Saadallah Al-Jabiri Square , according to the Syrian Observatory for Human Rights .

Though Syrian state-run media put the death toll at 34 , with 122 injured .

State television , meanwhile , aired footage of the carnage , which included the bloody and mangled bodies of men in military uniforms .

Why Syria turmoil threatens the Middle East

A fourth car bomb exploded near Aleppo 's chamber of commerce , the government and opposition said . The number of casualties from that incident was not immediately known .

The blasts highlight the escalating crisis in Aleppo , Syria 's most populous city , which has morphed into a major battleground between government and rebel forces .

Aleppo is also a major financial lifeline for President Bashar al-Assad 's government ; a rebel takeover of the city would deal a significant blow to four decades of Assad family rule .

Opposition groups later reported that `` a number of regime forces '' had been killed following the shelling of a Syrian military center near the town of Tal Abyad .

The deaths were not part of the Wednesday toll distributed by the opposition Local Coordination Committees of Syria . It said at least 200 people died across Syria on Wednesday , including 67 in Damascus and its suburbs and 29 in Idlib province .

More than 28,000 people have been killed across Syria since March 2011 , the LCC says . CNN is unable to independently confirm casualty reports , as the Syrian government has severely limited access by international journalists .

300,000 and counting : The crisis of Syria 's refugees

In other developments :

Shelling from Syria strikes house in Turkey

At least five people were killed and 10 injured when a shell landed on a house in the Turkish town of Akcakale , near the Syrian border , the town 's mayor said Wednesday .

The artillery shell was fired from the Syrian district of Tel Abayad , according to Turkey 's semiofficial Anadolu news agency . However , it is not yet clear what military force or group launched it .

Mayor Abdulhakim Ayhan said those killed were three children , their mother and a female neighbor . Two police officers were among those hurt , he said .

In return , Turkey fired on Syrian government targets .

`` Our armed forces on the border responded immediately to this atrocious attack within the rules of engagement , and points in Syria determined by radar were hit with artillery fire , '' a statement from Prime Minister Recep Tayyip Erdogan 's office said . `` Turkey , within the confines of the rules of engagement and international law , will never leave these types of provocations aimed at our national security unanswered . ''

UK steps up aid for Syrian refugees in Turkey

The United Kingdom will provide an additional 1 million pounds -LRB- $ 1.6 million -RRB- to help Syrian refugees through the Turkish winter , Deputy Prime Minister Nick Clegg said Wednesday .

`` Refugees from Syria face what is likely to be a bitterly cold winter . The supplies this extra funding will deliver will go some way to helping them through this difficult time , '' Clegg said in a written statement .

The United Kingdom has given 38.5 million pounds -LRB- $ 62 million -RRB- in humanitarian aid during the Syrian crisis . The added funding is expected to help about 10,000 refugees with supplies such as blankets , clothing and heaters

Turkey has taken in more than 93,000 Syrian refugees , more than any other country in the region .

Refugees in Turkey : Police are forcing us from homes

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Opposition groups reported that `` a number of regime forces '' had been killed after a shelling

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Two mortar shells also fell near the Municipal Palace , the Interior Ministry says

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A suicide bomber blew up a car bomb loaded with 500 kg bomb , the Interior Ministry says

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Syrian state-run media put the death toll from the blast at 34